Question: Solve the system of equations. $\begin{aligned} & 2x+7y = 3 \\\\ & x=-4y \end{aligned}$ $ x=$
Explanation: We are given that ${x}={-4y}$. Let's substitute this expression into the first equation and solve for $y$ as follows: $\begin{aligned} 2{x}+7y &= 3\\\\ 2\cdot({-4y})+7y&=3\\\\ -8y+7y&=3\\\\ -y&=3\\\\ y&=-3 \end{aligned}$ Since we now know that ${y}={-3}$, we can substitute this value in the second equation to solve for $x$ as follows: $ \begin{aligned} x &= -4\cdot{y} \\\\ x&=-4\cdot({-3})\\\\ x&=12 \end{aligned}$ This is the solution of the system: $\begin{aligned} &x = 12 \\\\ &y=-3 \end{aligned}$